Light device and method of assembling a light device

ABSTRACT

A thin light device includes a light circuit including a first light emitting unit mounted against a first side-edge surface of a printed circuit board, and a second light emitting unit mounted against a second side-edge surface of the printed circuit board. The first side-edge surface and the second side-edge surface of the printed circuit board are not coplanar. 
     In addition, the thin light device includes a light diffusion panel, and a light housing arranged to receive the light circuit and light diffusion panel. The light circuit is arranged next to the light diffusion panel, and the first and second light emitting units are arranged to emit light into the light diffusion panel.

The invention concerns a light device, comprising a light circuitincluding at least one light emitting unit, a light diffusion panel, anda light housing arranged to receive the light circuit and lightdiffusion panel.

The invention also concerns a method of assembling a relatively flat andelongated light device.

It is known to use decorative lighting in vehicles. For example, doorframes, in particular door steps, may be provided with integrated lightdevices that may emit light when opening a door. Such light devices areoftentimes provided with a print such that images and/or words aredisplayed. When the light device emits light, the printed image or wordis visible, even in dark circumstances. To mount these light devices indoor steps of vehicles such that they meet with the aesthetical andconstructional demands of automotive industry, these light devices haveto be relatively flat.

An example of such a light device is disclosed in the German utilitymodel DE102006002216. This light device is relatively flat, and is meantto be mounted in vehicle door steps. The flatness seems to be achievedby mounting Surface Mounted Device (SMD) type light emitting units on aflexible and relatively flat conducting plate. A transparent lightconducting basis plate having cut-through holes for the SMD lightemitting units is mounted on top of the conducting plate. A furthertransparent cover plate is placed on top of the basis plate. Protruding,three dimensional sign or image forming elements are provided in or onthe transparent cover plate.

A goal of the invention is to provide for an alternative, relativelyflat and elongated light device that can be readily mounted on or inconstruction parts.

This goal and/or other goals may be achieved by a light device accordingto claim 1.

A light housing is provided for mounting a light circuit and a lightdiffusion panel. The light circuit may comprise a printed circuit andlight emitting units. The light emitting units may emit light into theside edge of the light diffusion panel. In an embodiment, the lightemitting units may comprise light emitting diodes (LED's). By mountingthe light diffusion panel and the light circuit next to each other,stacking may be largely prevented, and the light device may remainrelatively flat.

By this arrangement, the light device may be elongated and flat, inparticular it may be less than three millimetres thick, moreparticularly less than or approximately equal to 2.5 millimetres. In anexemplary embodiment, the thickness of the light device is approximately1.6 millimetres or less. The thickness of the light device may bemeasured between the bottom and the top surface of the housing, whereinthe light circuit and the light diffusion panel, do not exceed above orbelow the housing. In an assembled condition, the light device may beessentially strip shaped.

Furthermore, the light device may be relatively elongated. For examplethe ratio between the width and length of the device may be at least1:5, although even longer relative elongation may be achieved, havingratios such as 1:8, 1:10, 1:20 or higher. With a light device accordingto the invention, relatively elongated light device may be achieved.Preferably, the light diffusion panel itself is relatively elongated,and the light circuit is arranged next to the light diffusion panelwhile taking up very little space, so that the dimensions of the lightdevice may be substantially determined by the light diffusion panel. Thelight emitting units may be arranged at the sides of the light diffusionpanel, to emit light into the side edges of the panel. The emitted lightmay be diffused and emitted over approximately the entire surface of thepanel.

Preferably, the light device comprises a light strip to be mounted in oronto a construction part of a vehicle, preferably in a vehicle frame fora door, window, or hood, or the like, more preferably in a vehicledoorstep. The light device may have a relatively small amount of partsso as to be assembled relatively easily. The light device may meet withthe aesthetical demands for automotive decoration or other types ofdecorative lighting. The arrangement of the light device is such thatstacking may be prevented. The light device may be arranged such that adecreased thickness and a reduced complexity may be achieved withrespect to existing light devices for similar purposes.

The relatively small thickness of the light device may allow the deviceto be mounted onto a standard construction part of a vehicle withoutnecessarily needing to provide a cut out in the respective constructionpart for receiving the light device. However, the light device may alsobe mounted in a cut out of the respective construction part, or betweenconstruction parts, or may be connected in any other manner to theconstruction part.

The light housing may comprise a first, elongated, cut out for the lightdiffusion panel, and at least one second cut out for the light circuit,wherein the second cut out may be arranged next to the first cut out. Atleast the first cut out may comprise a reflective surface. Also thesecond cut out may comprise a reflective surface. Upstanding wallsaround the respective cut outs may also be provided with reflectivesurfaces. Hence, the light that is emitted and diffused may be reflectedso that a substantial part of the emitted light may exit the diffusionpanel.

The light housing may comprise upstanding walls next to the cut outs,wherein in assembled condition the top surface of the upstanding wallsextends at approximately the same or a higher level as the top surfaceof the light diffusion panel and the light circuit. In this way theassembled parts may be prevented from protruding above the top surfaceof the housing and a relatively flat top surface may be achieved.

In an embodiment, the light device comprises a cover foil covering thetop surface of the light device. The foil may smoothen and/or protectthe top surface of the light device. In a further embodiment, the coverfoil may be provided with a print that is arranged to extend over thesurface of the light diffusion panel, wherein the light device havingsaid cover foil with print has a relatively smooth top surface. Thelight device may display signs and/or images that are printed on thecover foil by printing on the foil protrusions may be prevented. Thesigns and/or images may be readily printed on the foil. By applying aprinted foil, protruding signs may be prevented. Hence, the light devicemay remain flat while a relatively large amount of freedom in the designof the signs and images may be achieved.

The light emitting units may comprise LED's, or preferably miniaturesized light emitting units. The LED's may also comprise organic LED's.In an embodiment, the light emitting units may be arranged at one orboth of the short edges of the light diffusion panel, to emit light intothe respective short edge of the light diffusion panel. This may allowfor a relatively small width of the assembled light device, as well as areduction of complexity and necessary circuitry.

In an embodiment, the light diffusion panel may be provided with araster for optimizing the diffusion of light emitted into the panel. Theraster may be printed onto the top surface of the light diffusion paneland/or onto the cover foil.

In a further embodiment, a door frame, a window frame, or a hood framemay be provided, the frame being a construction part of a vehicle. Inthis description, the frame may be understood as the framework thatsurrounds the respective opening, for example the opening of the door,window or hood. The light device may be mounted into or onto such aframe. Preferably the frame may comprise a vehicle doorstep, wherein thelight device may be mounted in or onto said frame.

Above mentioned goals and/or other goals may also be achieved by amethod according to claim 16.

The light emitting units and the light diffusion panel may be assemblednext to each other in the light housing. The assembled light device mayfor example be mounted in or onto a vehicle frame, preferably a vehicledoor step.

In exemplary embodiments, the light housing may be injection mouldedand/or may comprise a strip wherein the cut outs for receiving the lightcircuit and light diffusion panel are milled. Preferably, the edges ofthe light diffusion panel are formed or finished using a laser.

According to a further aspect of the invention, there is provided a thinlight device according to claim 14. Design constraints may restrict ordetermine the size and type of the panel, and the number and arrangementof the light emitting units. But those constraints notwithstanding, auniform emission of light across a predetermined portion of the surfacemay nonetheless be achieved by patterning the light diffusion panel in amanner which compensates for those design constraints. Thus, it will beappreciated that a light device that is designed having the lightdiffusion panel according to this aspect of the invention affords a highdegree of design flexibility.

Exemplary embodiments of the invention are herein described withreference to the accompanying drawings, in which:

FIG. 1 schematically shows an exploded view in perspective of a firstlight device;

FIG. 2A and FIG. 2B schematically show a side view and top view,respectively of the light housing shown in FIG. 1;

FIG. 3 shows a top view of the light diffusion panel shown in FIG. 1;

FIG. 4 schematically shows a top view of the light circuit shown in FIG.1, including electrically cables for powering the circuit;

FIG. 5 shows a top view of the light circuit of FIG. 4, based on apicture of a prototype of the circuit;

FIG. 6 shows the cover foil of FIG. 1;

FIG. 7 shows an adhering foil for adhering the cover foil of FIG. 6 ontop of the first light device;

FIG. 8 schematically shows an exploded view in perspective of a secondlight device;

FIG. 9 shows the cover foil of FIG. 8;

FIG. 10A schematically shows the light diffusion panel of FIG. 8 andFIG. 10B shows the logo formed on the light diffusion panel;

FIG. 11 schematically shows a top view of the light circuit shown inFIG. 8;

FIG. 12 illustrates the outer dimensions of the light housing shown inFIG. 8;

FIG. 13 shows a top view of the second light device of FIG. 8 whenassembled;

FIG. 14 shows a schematic view of a light housing of a third lightdevice;

FIG. 15 shows a schematic view of the light diffusion panels of a thirdlight device;

FIG. 16 shows a foil cover of a third light device;

FIG. 17 shows a top view of the third light device; and

FIG. 18 shows a schematic representation of the layout of the variouslight circuits with respect to the light diffusion panels of FIG. 15.

In this description, where identical or corresponding parts exist,identical or corresponding reference numerals have been used. Theexemplary embodiments shown should not be construed to be limiting onthe scope of the invention in any manner and serve merely asillustration.

FIG. 1 shows an exploded view of parts that are to be assembled to forma first light device 1. In particular, a light housing 2, a lightdiffusion panel 3, a light circuit 4, and a cover foil 5 are shown,together forming the first light device 1.

The light circuit 4 comprises a printed circuit provided with LED's 6(with lenses). The LED's 6 are arranged at the short edges 7 of thelight diffusion panel 3, for example three LED's 6 at each short edge 7.An electrical conductor 8 is connected to the LED's 6, and is arrangedalongside a long edge 9 of the light diffusion panel 3. The lightcircuit 4 is arranged next to the light diffusion panel 3.

As shown in FIGS. 1, 2A and 2B, the light housing 2 has a first cut out10 having an elongated shape, the dimensions of which correspond withthe dimensions of the light diffusing panel 3. The thickness T1 of thelight diffusion panel 3 is approximately 1.5 millimetres. Likewise, thedepth D1 of the first cut out 10 is approximately 1.5 millimetres. Inother embodiments, the thickness T1 of the light diffusion panel 3 andthe depth D1 of the first cut out 10 may be less than 1.5 millimetres,for example, 1 millimetre or less.

Seen from above, the contour of the diffusion panel 3 and the first cutout 10 correspond so that the light diffusion panel 3 may be snuglyreceived into the first cut out 10. The light diffusion panel 3 has sideindentations 12 near the ends of the long side edges 9. The first cutout 10 has corresponding protrusions 13 that provide for a properfitting of the light diffusion panel 3 in the first cut out 10, andprevent sliding of the light diffusion panel 3 within the housing 2.

The light housing 2 has a second cut out 11 for mounting the lightcircuit 8. The maximum thickness T2 of the light circuit 8 is determinedby the thickness LED's 6. In the shown embodiment, this maximumthickness T2 is 2 millimetres, and further, the second cut outs 11 havea depth D2 of 2 millimetres. In other embodiments, the thickness T2 ofthe light circuit 4 and the depth D2 of the second cut out may be lessthan 2 millimetres, for example, 1.5 millimetres or less, or 1millimetre or less. Preferably, miniature LED's 6 or other miniaturelight emitting devices with limited thicknesses, having light emittingproperties adapted for its purpose are employed.

The second cut out 11 guides the conductors 8. Upstanding walls 14 ofthe housing 2 next to the second cut out 11 serve as protection for theconductors 8. The second cut out 11 directly borders the first cut out10 at the short sided ends of the second cut out 11, so that the LED's 6may directly emit light into the respective side edges 7 of the lightdiffusion panel 3. A small step 15 is present at the transition/borderbetween the first and second cut out 10, 11. The contour of the secondcut out 11 comprises protrusions 21 pointing inwards from the side wall14 for accommodating and/or positioning the LED's 6 and/or connectionelements for connecting the LED's 6 to the conductors 8.

In the shown embodiment, the thickness T3 of the light housing 2,between the top and bottom surface 12, is approximately 2.5 millimetres.The smallest thickness, for example, between the bottom surface of thesecond cut out 11 and the bottom 12 of the housing 2, is approximately0.5 millimetres. In further embodiments, the thickness T3 of the housing2 may be less than 2.5 millimetres, for example 1.6 millimetres or less.In other embodiments, the thickness T3 may be larger, for exampleapproximately 3 millimetres or less.

As shown in FIGS. 1, 2A and B, the length L1 of the housing 2 is, forexample, approximately 250 millimetres, while the width W1 isapproximately 37 millimetres. According to embodiments of the invention,the length L1 of the housing 2 may be at least five times the width W1of the housing 2, in particular at least seven times the width W1, moreparticularly at least ten times the width W1. The length L1 of thehousing 2 may be even larger with respect to the width W1. The relativelength may be adapted as to suit the application, for example a vehicledoor step.

The housing 2 comprises substantially insulating material, such as aplastic, for example acrylonitrile butadiene styrene (ABS), for exampleof the type magnum 3453. The material of the housing preferablycomprises non-transparent material so that emitted light does not exitthrough the housing 2. At the bottom and/or side walls of the cut outs10, 11 reflective material is preferably provided for reflecting thelight that is emitted by the LED's.

According to a preferred construction, the housing 2 may comprise aplate. The plate may be made by any suitable process, such as mouldingor extrusion, for example, injection moulding. The cut outs 10, 11 aremilled into the plate, for example, after moulding. For two cut outdepths D1, D2, two milling actions are employed. In another embodiment,the housing 2 including the cut outs 10, 11 may be integrally moulded,for example injection moulded.

The light diffusion panel 3 is shown in FIGS. 1 and 3. The lightdiffusion panel 3 may comprise an elongated substantially massive plate.The panel 3 is made of light conducting material, such as Plexiglass orPerspex or the like, for example plexiglass of the type superclear99560, which is a German industry standard.

In FIG. 3, the length L of the light diffusion panel 3 is approximately200 millimetres, and the width W of the light diffusion panel 3 isapproximately 23 millimetres. The panel 3 has an elongated shape.According to embodiments of the invention, the length of the panel 3 maybe at least five times, at least eight times, or at least ten times ormore larger than the width, or any other suitable length may be chosen.The length L of the light diffusion panel 3, may be adapted to theapplication.

For enhanced light diffusion, the panel 3 is preferably provided with araster 16. The raster 16 may comprises a print that is printed on thepanel 3. The print is provided on one side of the panel 3, in particularthe light exiting side of the panel 3. The raster 16 may, for example,comprise alternating dots, squares and/or lines, or an inverse printingof alternating dots, squares and/or lines, as shown in FIG. 3. Theraster 16 is arranged to locally alter the transparency so that thelight exiting the panel 3 is diffused. The print may be of any suitablecolour, for example, of the type that is known as UVPO weiss/60 HD,which is a German industry standard. A substantial part of the surfaceof the panel 3 may be provided with the raster 16.

FIGS. 4 and 5 show top views of the light circuit 4. The conductor 8comprises at least two isolated, preferably relatively flat cables 17.The two cables are protected by an insulating flat band 18. Theconductor 8 is arranged at least partly outside of the housing 2 toconnect to an outside power circuit and/or control circuit (not shown).Connections to the LED's and/or between conductors 8 may be made by anysuitable method, for example, by soldering. The LED's 6 are positionedat the outer ends of the housing 2 so that the light diffusion panel 3fits between the opposite LED's 6, preferably only leaving a narrowspace between the LED's 6 and the panel 3, for example, a space of 1millimetre or less, such as 0.05 millimetres.

FIG. 6 shows a cover foil 5 for covering the housing 2 with the lightcircuit 4 and the light diffusion panel 3. The outer surface dimensionsof the cover foil 5 are approximately the same as the outer dimensionsof the top surface of the housing 2, so that the cover foil 5substantially covers the entire top surface of the housing 2. The foil 5comprises a transparent part 18, which covers the light diffusion panel3, and a non-transparent part 19, for covering the light circuit 4and/or the top surface of the upstanding walls 14 of the housing 2.

The material of the cover foil 5 may be plexiglass, for example of thetype Plexiglass XT weiss matt 250 my 99547M, which is a German industrystandard. The top side of the foil 5 is relatively shiny. Thetransparent part 18 comprises a print having signs and/or images. Thesigns and/or images may for example comprise a letter, image, word,logo, photo, advertising, or the like. The print may be in black and/orwhite, or any colour and may have gradients. The print may locallyprevent or change the output of light so that the print can bedistinguished, at least when the light device emits light. For example,for the print the following colours may be used that are standardized inGerman industry. A certain white known as Marastar SR 170 Deckweiss Siebmay be used. A certain black known as Marastar SR 273 Deckschwarz Siebmay be used.

In an embodiment, the transparent part 18 of the foil 5 may comprise araster, for example instead of, or in addition to, the raster 16 oflight diffusion panel 3. The raster may be of the type known in Germanindustry as Drucklack UV 70/488. In another embodiment, the transparentpart 18 may comprise a cut through.

The cover foil 5 is adhered to the housing 2, in particular theupstanding walls 14 thereof, and/or the panel 3, by adhering means, suchas an adhering foil 20 (FIG. 7). The adhering foil 20 comprises a foilthat adheres on both sides so that the cover foil 5 may adhere to thehousing 2. The adhering foil 20 is arranged around the light diffusionpanel 3. The adhering foil may be of the type Kleber 3M® Scotch® F9469,which may be known as a German industry standard. In another embodiment,the cover foil 5 may for example be glued to the housing 2.

FIGS. 8 to 13 show a second light device 1. The constructional detailsand possible variations to those details presented in relation to thefirst light device apply mutatis mutandis to the second light device,the second light device differing only in the respects shown in thedrawings or explicitly mentioned below.

Referring to FIG. 8, the first cut out 10 and the second cut out 11extend down to the same depth within the housing 2, i.e. the step 15 hasbeen eliminated. The light circuit 4 comprises a thin substrate/circuitboard 30 having a thickness of 0.1 millimetre on which is mounted a lineof LED's 6 (without lenses). The LED's 6 have an individual height of1.2 millimetre resulting in the light circuit 4 having an overall heightof 1.3 millimetre. The light diffusion panel 3 has a height of 1.5millimetre. When the second light device 1 is assembled, the lightcircuit 4 is located within the first cut out 10, the light diffusionpanel 3 located within the second cut out 11 and the cover foil ormember 5 closes the housing 2 as shown in FIG. 13. The power supplycable 17 passes through a channel (not shown) formed in a wall of thehousing.

Since the nominal height/thickness of the light diffusion panel is 1.5millimetre and that of the light circuit 4 is 1.3 millimetre, a 0.2millimetre environmental tolerance window is created. Such a tolerancewindow is beneficial when the second light device is used on a vehiclewhich may be required to operate in extreme climatic conditions.

Since the light diffusion panel 3 is edge-lit from only one edge, theraster 16 is patterned to make uniform the amount of light exiting thepanel 3 per unit area across the whole surface of the panel 3. Broadlyspeaking, this requires making regions near to the light circuit endless transparent and regions remote from the light circuit end moretransparent. As a result, the failure of a single LED 6 has much lessnegative impact on (the user's perception of) the uniformity of lightemission from the second light device 1 than is the case when a singleLED 6 fails in the first light device 1.

A further advantage of the second light device 1 over the first lightdevice is that since the overall height/depth of the light circuit 4 isless than the light diffusion panel 3, the step 16 can be eliminated andhence the thickness of the housing 2 can be reduced, whereby the overallthickness of the second light device 1 can be as little as 2 millimetre.

It has been found that in order to avoid local patches of non-uniformlight emission near even slight imperfections in the edges of the lightdiffusion panel, the edges should be created or finished by laser.

FIGS. 14 to 18 show a third light device 1. The third light device 1 isconstructed in a generally similar manner to the first and second lightdevices from a light housing 2, a light diffusion panel 3, and a lightcircuit 4, and a cover foil 5. The constructional details and possiblevariations to those details presented in relation to the first or secondlight devices apply mutatis mutandis to the third light device, thethird light device differing only in the respects shown in the drawingsor explicitly mentioned below.

Referring to FIG. 14, the light housing 2 comprises cut out regions toreceive light diffusion panels and light circuits as per the previousembodiments, but these are not distinguishable in the drawing. Referringto FIG. 15, the third light device 1 comprises three discrete lightdiffusion panels 3 a, 3 b, 3 c. The light diffusion panel 3 a has anelongate aperture 35 a, extending along most of its length and extendingcompletely through the depth of the panel. The light diffusion panel 3 chas a similar aperture 35 c. Referring to FIG. 16, the cover foil 5 hasa transparent region 5 a corresponding to the image that it is to bedisplayed. First and second irregularly shaped substrates 40, 41, havinga thickness of 0.5 millimetre, are mounted in the interstices shown inFIG. 15 between the panels 3 a, 3 b and panels 3 b, 3 c, respectively.The substrates 40, 41 carry the light sources to illuminate the panels 3a, 3 b, 3 c as described below.

Referring to FIG. 18, the substrate 40 carries a line of LED's 6 aoriented at 76, 7° to the longitudinal axis of the device 1 forinjecting light into the panel 3 a. The substrate 40 and the LED's 6 acomprise a first light circuit 4 a for the panel 3 a. The substrate 41carries a line of LED's 6 c also oriented at 76, 7° to the longitudinalaxis of the device 1 for injecting light into the panel 3 c. Thesubstrate 41 and the LED's 6 c comprise a third light circuit 4 c forthe panel 3 c. In addition, LED's 6 b ₁, and 6 b ₂ mounted on oppositesides of the substrate 40 and LED's 6 b ₃ and 6 b ₄ mounted on oppositesides of the substrate 41 inject light into the panel 4 b. All the LED's6 b ₁, 6 b ₂, 6 b ₃, 6 b ₄ are oriented at 45° to the longitudinal axisof the device 1. The LED's 6 b ₁, 6 b ₂, 6 b ₃, 6 b ₄ and the substrates40, 41 comprise a second light circuit 4 for the panel 3 b. In otherembodiments (not shown), the LED's could be mounted at different angles.FIG. 17 shows a fully-assembled third device 11.

In common with the second light device 1, the panels 3 a-c are providedwith rasters tailored to the specific geometry of the device and theproperties of the light sources/circuits to achieve the requireduniformity of light distribution. In this instance, it will beappreciated that the design of the rasters takes into account the factthat the panels 3 a, 3 c are not continuous members but include elongateapertures 35 a, 35 c. The elongate apertures 35 a, 35 c are provided asthere is no need for the diffusion panels to be present in thoseregions, those regions being obscured by non-transparent portions of thecovering foil/member 5. It will be appreciated that the patterning onthe light diffusion panel enables the LED's to make use of the small andirregularly shaped interstitial regions between the panels 3 a, 3 b and3 b, 3 c while still achieving the required uniformity of lightemission.

Advantageously, the light devices 1 may be mounted in or onto a doorstepof an automotive vehicle such as a car, truck, or busses. They may bemounted in or onto the middle consoles, window frames, door frames, hoodframes, panels, foot mats, gas-pedals, or other construction parts ofthe vehicles. Other applications may include two or three wheeled motorvehicles, and/or airplanes, and/or public transport vehicles such astrains, metros, trams, etc. The light devices may also be provided inother applications, such as, for example, ambient lighting, furniture,doormats, door edges, frames in buildings, rooms, etc. The light devicesmay for example be used for decorative, advertising and/or informativepurposes. In an embodiment, the housing 2 and/or the diffusion panel 3may comprise relatively flexible material, so that a relatively flexiblelight device 1 may be achieved, that may be arranged on or into curvedframes.

It shall be obvious that the invention is not limited in any way to theembodiments that are represented in the description and the drawings.Many variations and combinations are possible. Combinations of one ormore aspects of the embodiments or combinations of differentembodiments, and all comparable variations are possible, as the skilledperson will recognise.

1-19. (canceled)
 20. A thin light device, comprising: a light circuitincluding a first light emitting unit mounted against a first side-edgesurface of a printed circuit board, and a second light emitting unitmounted against a second side-edge surface of the printed circuit board,wherein the first side-edge surface and the second side-edge surface ofthe printed circuit board are not coplanar, a light diffusion panel, anda light housing arranged to receive the light circuit and lightdiffusion panel, wherein the light circuit is arranged next to the lightdiffusion panel, and the first and second light emitting units arearranged to emit light into the light diffusion panel.
 21. The thinlight device according to claim 20, wherein the first side-edge surfaceof the printed circuit board is orthogonal to a component-pad-sidesurface of the printed circuit board.
 22. The light device according toclaim 20, wherein the top surface of the light diffusion panel is higherthan the top surface of the light circuit by at least 1 millimeter. 23.The light device according to claim 20, wherein the light devicecomprises a light strip to be mounted in or onto a construction part ofa vehicle.
 24. The light device according to claim 23, wherein theconstruction part of a vehicle includes a door frame, window frame, hoodframe, or a doorstep.
 25. The light device according to claim 20,wherein the thickness of the assembled light device is 2.5 millimetersor less.
 26. The light device according to claim 20, wherein thethickness of the assembled light device is 1.6 millimeters or less. 27.The light device according to claim 20, wherein the light housingcomprises a first, elongated, cutout for the light diffusion panel, andat least one second cutout for the light circuit, and wherein the secondcutout is arranged next to the first cutout.
 28. The light deviceaccording to claim 27, wherein the light housing comprises upstandingwalls next to the cutouts, and wherein in assembled condition the topsurface of the upstanding walls extends at the same or a higher level asthe top surface of the light diffusion panel or the light circuit. 29.The light device according to claim 20, wherein the light devicecomprises a cover foil covering the top surface of the light device. 30.The light device according to claim 29, wherein the cover foil isprovided with a print that is arranged to extend over the surface of thelight diffusion panel, and wherein the light device having said coverfoil with print has a smooth top surface.
 31. The light device accordingclaim 20, wherein the at least one light emitting unit comprises a lightemitting diode.
 32. The light device according to claim 20, wherein theat least one light emitting unit is arranged at a short edge of thelight diffusion panel, to emit light into the short edge of the lightdiffusion panel.
 33. The light device according to claim 20, whereinlight emitting units are arranged at two short edges of the lightdiffusion panel.
 34. The light device according to claim 20, wherein thelight diffusion panel is provided with a raster patterned to achieve auniform emission of light across a predetermined portion of the surfaceof the light diffusion panel.
 35. The light device according to claim34, wherein a single side edge of the panel is configured to transmitlight directly from the light circuit.
 36. The light device according toclaim 20, wherein the light diffusion panel has a thickness of threemillimeters or less and a length that is at least five times its width.37. The light device according to claim 36, wherein the housing has athickness of three millimeters or less and a length that is at leastfive times its width.
 38. The light device according to claim 20,wherein the first side-edge surface and the second side-edge surface ofthe printed circuit board are flat.
 39. The light device according toclaim 20, wherein the first side-edge surface and the second side-edgesurface of the printed circuit board are parallel.